Apparatus and methods for medical applications of laser-driven microfuild pumps

ABSTRACT

An apparatus for controlling a cylinder by a microfluidic stream includes a microtube, a first laser-driven photoacoustic microfluid pump (LDMP), and a fiber optic element. The microtube includes a fluid and a cylinder. The fiber optic element includes a first end and a second end. The first end is disposed on the first LDMP and the second end is disposed in a first end portion of the microtube. The first LDMP is configured to generate a directional fluidic jet from the fluid and to push the cylinder in a direction away from the second end of the fiber optic element.

CROSS-REFERENCE TO RELATED APPLICATION/CLAIM OF PRIORITY

This application claims the benefit of, and priority to, U.S. Provisional Pat. Application No. 63/293,897, filed on Dec. 27, 2021, the entire contents of each are hereby incorporated herein by reference.

TECHNICAL FIELD

The present application relates to apparatus and methods for medical applications of laser-driven microfluid pumps, and in particular, to apparatus and methods for medical applications of laser driven photoacoustic microfluid pumps.

BACKGROUND

The process of converting (or transforming) one form of energy into another is often referred to as transduction. A transducer is a device that is typically employed to perform such a function, and transducers can be characterized by the direction in which the physical system (e.g., pressure, temperature, sound waves, etc.) passes through them. For example, a sensor is a type of transducer that receives and responds to a signal/stimulus from a physical system (e.g., temperature) and produces an electrical signal that represents information about the physical system. An actuator, on the other hand, is a transducer that controls/generates a physical system (e.g., sound waves), in response to some electrical signal. For example, a speaker transforms an electrical signal of a recording to mechanical sound waves.

As noted above, one form of energy can be transformed into another. These energy forms may include, for example, mechanical, electrical, chemical, electromagnetic, thermal, and acoustic energy. Research has been conducted to explore transforming other forms of energy, such as transforming light energy (e.g., high-energy photons) to mechanical energy. Transforming light energy into some form of mechanical energy requires efficient momentum transfer, and that is difficult to attain. An efficient system that can perform such a transformation is desired.

SUMMARY

This disclosure relates to apparatus and methods for medical applications of laser-driven photoacoustic microfluid pumps. In accordance with aspects of the present disclosure, an apparatus for controlling a cylinder by a microfluidic stream includes a microtube, a first laser-driven photoacoustic microfluid pump (LDMP), and a fiber optic element. The microtube includes a fluid and a cylinder. The fiber optic element includes a first end and a second end. The first end is disposed on the first LDMP and the second end is disposed in a first end portion of the microtube. The first LDMP is configured to generate a directional fluidic jet from the fluid, and to push the cylinder in a first direction away from the second end of the fiber optic element.

In an aspect of the present disclosure, the first LDMP may include a substrate having a first side and a second side and a layer of photoacoustic material disposed on the first side of the substrate. The layer of photoacoustic material may be configured to generate a directional ultrasound wave in response to a laser beam impinging on the layer. The photoacoustic layer may include nanoparticles.

In accordance with aspects of the present disclosure, the apparatus may further include a second LDMP and a second fiber optic element. The second fiber optic element includes a first end and a second end. The first end is configured to be disposed on the second LDMP and the second end is configured to be disposed in a second end portion of the microtube. The second LDMP is configured to generate a directional fluidic jet from the fluid, and to push the cylinder in a second direction different than the first direction.

In an aspect of the present disclosure, the second end of the fiber optic element may include a surface implanted with metal.

In an aspect of the present disclosure, a first end of the second fiber optic element may include a surface implanted with metal.

In accordance with aspects of the present disclosure, the cylinder may include a first end including a surface implanted with metal.

In accordance with aspects of the present disclosure, the cylinder may include a second end that includes a surface implanted with metal.

In accordance with aspects of the present disclosure, the fluid may include at least one of water, blood, plasma, or body fluid.

In an aspect of the present disclosure, the microtube may be disposed on a microfluidic chip.

In accordance with aspects of the present disclosure, a method for controlling a cylinder by microfluidic streaming is described. The method includes generating a directional ultrasound wave, in a microtube, based on directing a laser beam at a first laser-driven photoacoustic microfluid pump (LDMP). The microtube includes a fluid and a cylinder. The method further includes thermally expanding and contracting a photoacoustic layer implanted on an end portion of the cylinder in response to the laser beam striking the photoacoustic layer, and moving the cylinder in a direction away from the first LDMP based on the thermal expansion and contraction.

In an aspect of the present disclosure, the method may further include: generating a second directional ultrasound wave, in the microtube, based on directing a second laser beam at a second laser-driven photoacoustic microfluid pump; thermally expanding and contracting a second photoacoustic layer implanted on a second end portion of the cylinder, in response to the second laser beam striking the second photoacoustic layer; and moving the cylinder in a direction away from the second LDMP based on the thermal expansion and contraction.

In accordance with aspects of the present disclosure, an apparatus for generating a vortex in a microfluidic chip, includes a laser-driven photoacoustic microfluid pump (LDMP) configured to generate a vortex, a transparent substrate, a fiber optic element, and microchannels including a fluid. The fiber optic element includes a first end and a second end, where the first end is configured to be disposed on the LDMP and the second end is configured to be disposed in a first surface of the substrate.

In an aspect of the present disclosure, the transparent substrate may include an area implanted with metal.

In accordance with aspects of the present disclosure, the second end of the fiber optic element may include a surface implanted with metal.

In accordance with aspects of the present disclosure, the fluid may include at least one of water, blood, plasma, or body fluid.

In accordance with aspects of the present disclosure, the apparatus may further include a second LDMP configured to generate a vortex and a second fiber optic element. The second fiber optic element includes a first end and a second end. The first end is configured to be disposed on a second LDMP and the second end is configured to be disposed in a first surface of the substrate.

In an aspect of the present disclosure, the first fiber optic element may be inserted into the microfluidic chip at a first angle relative to a first surface of the microfluidic chip.

In accordance with aspects of the present disclosure, the second fiber optic element may be inserted into the microfluidic chip at a second angle relative to the first surface of the microfluidic chip, wherein the second angle is different than the first angle.

In accordance with aspects of the present disclosure, the microfluidic chip is configured for microfluidic mixing of a sample with the fluid.

In accordance with aspects of the present disclosure, the microfluidic chip may be configured for at least one of microfluidic surgery or cleaning an artery.

Further details and aspects of exemplary aspects of the present disclosure are described in more detail below with reference to the appended figures.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the features and advantages of the disclosed technology will be obtained by reference to the following detailed description that sets forth illustrative aspects, in which the principles of the technology are utilized, and the accompanying figures of which:

FIG. 1 depicts an apparatus for moving a cylinder using microfluidic jets, in accordance with aspects of the present disclosure;

FIG. 2 depicts another exemplary apparatus for moving a cylinder using microfluidic jets, in accordance with aspects of the present disclosure;

FIGS. 3A-D depict laser streaming generation on the end of a fiber optic element with gold (Au) ion implantation pushing the cylinder to migrate, in accordance with aspects of the present disclosure;

FIG. 4 depicts an apparatus for generating a vortex, in accordance with aspects of the present disclosure;

FIG. 5 depicts another exemplary apparatus for generating a vortex, in accordance with aspects of the present disclosure;

FIG. 6 depicts another exemplary apparatus for generating a vortex, showing the head of the fiber optic element(s) at different angles, in accordance with aspects of the present disclosure;

FIG. 7 depicts an apparatus 700 configured for moving objects 708 using a microfluidic jet, in accordance with aspects of the present disclosure;

FIGS. 8A-F depicts laser streaming on the tip of a needle, in accordance with aspects of the present disclosure;

FIGS. 9A-D depicts the generation of a jet by a laser source, in accordance with aspects of the present disclosure;

FIGS. 10A-L depicts laser streaming on the tip of a needle at different angles, in accordance with aspects of the present disclosure; and

FIGS. 11A-I depicts acoustic pressure field, intensity contour and velocity distribution of laser streaming on the tip of the needle, in accordance with aspects of the present disclosure.

Further details and aspects of various aspects of the present disclosure are described in more detail below with reference to the appended figures.

DETAILED DESCRIPTION

This disclosure relates to apparatus and methods for medical applications of laser-driven photoacoustic microfluid pumps (LDMP).

Although the present disclosure will be described in terms of specific aspects, it will be readily apparent to those skilled in this art that various modifications, rearrangements, and substitutions may be made without departing from the spirit of the present disclosure. The scope of the present disclosure is defined by the claims appended hereto.

For purposes of promoting an understanding of the principles of the present disclosure, reference will now be made to exemplary aspects illustrated in the drawings, and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the present disclosure is thereby intended. Any alterations and further modifications of the inventive features illustrated herein, and any additional applications of the principles of the present disclosure as illustrated herein, which would occur to one skilled in the relevant art and having possession of this disclosure, are to be considered within the scope of the present disclosure.

Based on their operating principle, micropumps can be divided into two groups: mechanical and nonmechanical. Developed in the 1980s with the emergence of microelectromechanical systems, a mechanical micropump is a miniaturized version of a macroscopic pump, made of moving parts such as valves and membranes that can displace fluid directly. Although nonmechanical micropumps have no moving parts, they still require carefully fabricated microstructures and electrical contacts to generate thermal, electrical, magnetic, or acoustic stimulus to drive the fluids. While the performance of micropumps improved as the fabrication technique evolved, the principle and design of micropumps have remained almost the same over past decades. In various aspects, the micropump has no moving parts or electrodes, thus requires no micro- or nanofabrication. The size, number, location, and timing of the micropumps may be remotely controlled, reconfigured, and programmed in real-time. The pump may include a semitransparent plasmonic quartz window. The pump may be based on the principle of photoacoustic laser streaming: an ultrasound wave generated by a resonant laser pulse drives fluid through acoustic streaming. The whole surface of the quartz window may be covered with a plasmonic layer. An ultrasound wave can be generated from any point on the window, making it a micropump launch pad.

With reference to FIGS. 1 and 2 , an apparatus 100 a, 100 b for moving a cylinder 108 using microfluidic jets is shown. The apparatus 100 a, 100 b may include one or more laser-driven photoacoustic microfluid pump(s) (LDMP) 180 a, 180 b, one or more fiber optic elements 104, 106, and a microtube 102. The apparatus 100 a, 100 b may form a gate in a channel, enabling the opening of the gate, closing of the gate and/or selecting a desirable channel source. The apparatus 100 a, 100 b enables a liquid logic in a liquid network. For example, operating as a gate, the apparatus 100 a, 100 b may be used to selectively enable or disable a path for fluid to flow. The cylinder 108 may be substantially circular in cross-section or may include other geometries.

The LDMP(s) 180 a, 180 b, is made by ion implantation of gold (Au) atoms (or other metallic atoms) into a solid substrate such as quartz, glass, or other transparent materials. The substrate size can be small, for example, sub-mm size. The gold (or other metal) may be implanted into a large thin substrate. The gold ions may be implanted within about 50 nm below the surface. A relatively high dose may be used so that a sufficient Au nanoparticle concentration and corresponding optical absorption can be obtained. Then the thin substrate may be diced into a small size LDMP.

The microtube 102 (e.g., an open tube capillary) includes a first end portion 102 a and a second end portion 102 b. The microtube 102 further includes a fluid 107 and a cylinder 108 movably disposed in the microtube 102. The cylinder 108 includes a first end portion 108a and a second end portion 108 b. In aspects, the surface of the first end portion 108 a and the surface of the second end portion 108 b of the cylinder 108 may be implanted with Au and/or other metals to generate streaming to push the cylinder 108 to migrate left or right (FIG. 1 ). In aspects, the cylinder 108 may be replaced with a sphere (e.g., a glass ball, not shown) with implanted metal such as gold (Au) ions on its side. In aspects, the microtube 102 may include a “T” shape. The cylinder 108 may be pushed in the fluid by the laser to block the “T” or enable the fluid to flow through the “T.”

In aspects, the cylinder 108 may be a drug delivery device. In aspects, the first end portion 108a may be a needle and have an opening and the surface of the second end portion 108b of the cylinder 108 may be implanted with Au and/or other metals to generate streaming to push the cylinder 108 to migrate towards tissue, so that the needle may pierce tissue and deliver a drug. The apparatus 100 a, 100 b, for example, can physically deliver a cancer drug to a tumor location to enhance the efficacy, and reduced unwanted side effects that are associated with using the blood stream to deliver drugs. The apparatus 100 a, 100 b, enable the acute delivery of a drug in a desired location.

The one or more fiber optic elements 104, 106 are disposed, respectively in each end portion 102 a, 102 b of the micro tube 102, and are configured to communicate the laser light from the LDMP(s) 180 a, 180 b to the Au-implanted region. The fiber optic elements 104, 106 include a first end portion 104 a, 106 a and a second end portion 104 b, 106 b. The first end portion 104 a, 106 a may be disposed on the LDMP 180. The first end portion 102 a of microtube 102 may be disposed on the fiber optic element 104. The second end portion 102 b of microtube 102 may be disposed on the fiber optic element 106. In aspects, a surface of the first end portion 104 a, 106 a of the fiber optic elements 104, 106 may be implanted with Au and/or other metals to generate streaming to push the cylinder 108 to migrate left or right (FIG. 2 ). In aspects, the one or more fiber optic elements 104, 106 may include but are not limited to fibers, catheters, co-axial tubing, and/or combinations thereof. The fibers, catheters, co-axial tubing may be used in parallel.

The LDMP 180 a, 180 b may be configured to generate a directional fluidic jet of the fluid 107 to move the cylinder 108 from a proximal portion of the microtube 102 to a distal portion of the microtube 102 and vice-versa. It is contemplated that the fluidic jet may include gases and/or liquids. The size of the system may also depend on the application. The LDMP may then be attached (mounted, glued, or fused) in contact with a fiber optic elements 104, 106 to bring the laser to the LDMP and produce a fluidic jet. Metal atoms may be implanted directly in the end of the fiber optic elements 104, 106 to make the end as the fluidic jet head whenever the laser is transported through the fiber to the head. It is contemplated that the laser may be any wavelength in the range of approximately 180 nm-1 mm. The fiber optic elements 104, 106 may range in diameter from approximately a fraction of a micron to over several millimeters. The use of laser light as a power source enables very flexible and small profile tools that could establish or enhance fluid flow in the body. These would operate similar to a “ramjet” engine where fluid is brought into a chamber in a hollow tube, and accelerated by LDMP pumps (e.g., single, multiple, and/or located in multiple parts of the lumen). This flow may be modified in multiple ways to enhance the efficacy of the application. For example, by providing a constant flow rate, with such flow rate adjusted by the amount of laser light. Pulsatile flow could be created to simulate the physiological activity of the heart. This could be accomplished by cycling the laser on or off. In addition, ultrasonic or hypersonic flow cycles could also be created to enhance certain tool activities, such as dislodging thrombus. For example, multidirectional flows may be created by adjusting the direction of the laser. This could include creating a vortex to enhance certain applications. It is contemplated that designs of these pumps may include various fluid inlets and outlets, and/or multiple windows, to optimize for various applications.

The fluid 107 may include water, blood, plasma, body fluid, ethylene glycol, and/or any other fluid, depending on medical or surgical applications. In aspects, the fluid may include a combination of fluids such as water with ethylene glycol to produce fluids with different viscosities. Jet cross-section may be 0.1 mm diameter or less with the velocity of the jet fluid up to a few cm/sec, depending on the power of the laser inducing the fluidic jet in the forward direction.

FIGS. 3A-D depict laser streaming generation on the end of the fiber optic element 104 of the apparatus 100 a, 100 b of FIGS. 1 and 2 , with Au ion implantation pushing the cylinder 108 to migrate. FIG. 3A shows an experimental demonstration of laser streaming from a fiber optic element 104 to move a gold implanted cylinder 108. The surface of one end of the cylinder 108 is implanted with gold, for example, at the dose of approximately 2×10¹⁷ /cm². The laser streaming occurs from the gold implanted on the end of the cylinder 108 when the approximately 10-15 mW pulse (150 nm) laser with the wavelength of about 527 nm hits the other end. The laser streaming pushes particles in the glass tube. These types of pumps will offer numerous advantages over other mechanical based pumps, including, but not limited to non-contact flow, thus reducing cell damage and thrombosis caused by traditional mechanical pumps; very small size and ability to drive fluid anywhere you can get laser energy; and/or no electrical or mechanical energy transmission needed to operate.

Referring to FIG. 4 , an apparatus 500 a for generating a vortex is shown, in accordance with aspects of the present disclosure. The aim of microfluidic mixing is to achieve a thorough and rapid mixing of multiple samples in microscale devices. In such devices, sample mixing is essentially achieved by enhancing the diffusion effect between the different species flows. Mixing in microfluidic devices traditionally presents a challenge due to laminar flows in microchannels, which result from low Reynolds numbers determined by the channel’s hydraulic diameter, flow velocity, and solution’s kinetic viscosity. If the Reynolds number is too low, then the fluids will not mix. The disclosed apparatus solves many of these problems and enables thorough mixing in microfluidic devices. The apparatus 500 a generally includes a transparent substrate 510, a microfluidic chip 520 disposed on the transparent substrate, a region 530 implanted with a metal element such as Au ions, an LDMP 580, and one or more fiber optic elements 104.

The transparent substrate 510 may be made of glass, quartz, and/or other materials that would enable laser light to pass through.

The microfluidic chip 520 includes a set of micro-channels etched or molded into a material (e.g., glass, silicon, or a polymer such as polydimethylsiloxane). The microfluidic chip 520 may include any number of channels. For example, the microfluidic chip 520 may include, but is not limited to a 30 by 30 array of channels. The micro-channels forming the microfluidic chip 520 are connected together in order to achieve the desired features such as mixing, pumping, sorting, or controlling a biochemical environment. The microfluidic chip 520 includes a fluid 107 disposed in the microchannels. The fluid 107 may include water, blood, plasma, body fluid, ethylene glycol, and/or any other fluid. In aspects, the microfluidic chip may be configured for microfluidic surgery and/or cleaning an artery.

The implanted region 530 may be implanted with a metal element such as Au and/or other metal elements. The region may be the entire surface of the transparent substrate 510, or a smaller portion of the transparent substrate 510 to form vortex streaming. In aspects, the vortex streaming may occur at multiple spots and may include a pattern or arrangement of vortices.

The fiber optic element 104 is configured to deliver laser light to the implanted region 530. The laser intensity may be controlled streaming for vortex formation (e.g., active mixing, sorting, and/or separation). In aspects, the fiber optic element 104 may include ion implantation on an end portion 104 a of the fiber optic element 104. In aspects, the end portion 104 a of the fiber optic element 104 (i.e., the head) may be inserted into the microfluidic chip during fabrication.

The apparatus 500 a supports using any suitable numbers of wells, such as a 96-well, and/or a 384-well implementation for mixing in biochemistry, biomedical research, and/or pharmaceutical research using micro/nano fluidity. The disclosed technology has the benefit of enabling effective mixing even for a small volume experiment.

FIG. 5 depicts another exemplary apparatus 500 b for generating a vortex similar to the apparatus in FIG. 4 , except the implanted region 530 is shown as many smaller regions.

FIG. 6 depicts another exemplary apparatus 500 c for generating a vortex, showing the head of the fiber optic element(s) at different angles relative to the transparent substrate 510. In aspects, the insertion direction of the fiber optic element 104 may be in any designed angle relative to the transparent substrate 510 based on the purpose for the desired functions. For example, fiber optic element(s) 104 inserted on one end of the microfluidic chip 520 may be used to generate steaming, which enables manipulation of a microfluid field.

FIG. 7 depicts an apparatus 700 configured for moving objects 708 using a microfluidic jet. The apparatus generally includes a microtube 702 that includes a fluid 107, and a fiber optic element 706 that may include a bundle of fibers (e.g., 10 to 20 fibers). The fiber optic element 706 may be “U” and/or “trombone” shaped. The fiber optic element 706 includes a first end portion that is disposed on a laser source 704 and a second end portion that is disposed in the fluid 107 that is infused with metal ions such as Au-ions. When the laser is activated, it causes the fluid to flow in a direction away form the open end 702 a of the microtube 702, causing a vacuum and/or a suction, which may be used to manipulate an object 708. By turning off the laser, the apparatus 700 can release the object 708.

Referring to FIGS. 8A-F, laser streaming on the tip of a needle is shown. The needle may be made of any material that can absorb light and convert optical energy to ultrasound. Although a needle is shown, other shapes are contemplated to be within the disclosure. By employing a commonly used sewing needle with a sharp tip (FIG. 8A), the metal implanted surface may be shrunk. As shown in FIG. 8B, the 527-nm laser is focused horizontally on the needle tip, and the 633-nm laser is used to image the motion of the liquid. A jet is generated from the needle tip, as shown in FIG. 8C. However, due to the small size of the surface, the jet flows along the body of the needle, and the liquid is replenished from nearly the full space in which the needle is immersed, similar to what is observed for a jet generated from the fiber end. FIGS. 8D-F show the enlarged snapshots of the jet flows. When the orientation of the needle is changed, the jet is always along the axis of the needle. Two typical cases are shown in FIGS. 8D and 8E, where the needle is tilted by 10° and 25° with respect to the horizontal direction, the angles of jets are also 10° and 25°. With a fixed tilting angle of the needle, when the focal point of the laser is slightly moved, the direction of the jet will change. Taking the 10°-tilting-angle needle as an example, when the laser beam is focused right at the needle tip, the jet flows along the needle (shown in FIG. 8E). However, when the laser beam is focused slightly below the tip, a horizontal jet is generated (shown in FIG. 8F, the laser beam remains horizontal). In this case, the local surface profile at the focal point has changed, thus the direction of the jet is no longer along the axis of the needle. Accordingly, the flow direction may be controlled not only by tailoring the surface profile, but, more conveniently, also by adjusting the laser focal point.

FIGS. 9A-D shows a sequence of high-speed images (500 fps, 2 ms exposure time, by a high-speed camera) of the fluid flow after the striking of a laser pulse. It can be seen from FIG. 9A that the fluid is initially stationary. After the arrival of the laser pulse, as shown in FIG. 9B, the fluid is set into motion, which can be observed by the trajectory of the tracer particles (3.2 µm, emission wavelength: 612 nm). It is observed that tracer particles (marked by 1, 2, 3, at a distance of ~150 µm from the surface) show longer trajectories, while particles (4, 5, 6, at a distance of ~50 µm from the surface) show shorter trajectories and particles (7, 8, very close to the surface) remain motionless. Since the camera constantly integrates the light signal reflected by the particles during the 2-ms exposure time, motionless particles (7, 8) appear as bright spots in the image, whereas the trace is dimmer for a moving particle and the length of the trace indicates the speed. Thus, it is reasonable to assume that the fluid ~150 µm away from the surface (represented by particles 1, 2, 3) starts to move first and quickly reaches to the highest speed. Noticing that the trace directions of particles (4, 6) in FIG. 9B point to the original positions of particles (1, 2, 3), the fluid (represented by particles 4, 5, 6) starts to replenish it after the original liquid here moves away. Throughout the whole process, particles (7, 8) never change their positions, indicating that the liquid near the surface remains motionless. Clearly, the generation of laser streaming is drastically different from that due to laser ablation, laser-induced forward transfer, or bubble cavitation jet, in which the highest speed of the jet is always observed near the solid surface. Instead of the embedded Au particles, the laser is directly absorbed by the metal, and a thin layer of transient vapor is generated on the metal surface. The volume change of water vapor cause ultrasonic vibrations, and further induces an ultrasonic wave in the liquid, leading to an acoustic jet flow.

Referring to FIGS. 10A-L, laser streaming on the tip of a needle at different angles, using a numerical model, is shown. The ultrasound field responsible for laser streaming originates from the volume change of water vapor induced by laser heating. To examine various aspects of laser streaming, especially the determination of streaming direction, the model may be simplified without considering the laser heating and transient vapor generation for ease of computation. In the model, the laser-induced ultrasonic vibration of water vapor is approximated by a harmonic pressure boundary condition with a Gaussian spatial distribution on the surface of the needle tip, as the intensity of laser beam is normally distributed and the discontinuity of pressure distribution at the edge of the thin layer of vapor can be avoided. The center of Gaussian distribution is set to coincide with the laser focal point, representing the location of the incident laser beam. FIG. 10A shows the snapshot of a jet that spurts from the needle tip orientated with a 10° tilting angle. The jet starts at dozens of microns away from the surface of the needle tip, and then flows along the needle. FIG. 10B shows the corresponding pressure distribution on the needle surface when the laser beam is focused on the needle tip with a 10° tilting angle. FIG. 10C shows the flow distribution of the resulting acoustic streaming field. It can be found that the direction and the general characteristics of the jet flow agree reasonably well with the experimental observations. The experimental and simulation results for a needle tip oriented at 30° are shown in FIGS. 10D-F. It can be deduced that the jet always remains the same direction as the axis of the needle when the laser beam is focused at the very tip of the needle.

Simulations for laser streaming are performed where the laser beam is focused slightly below or above the tip of the needle. In the experiment, when the laser focal point is swept near the very tip of a 20°-tilt-angle needle from the bottom up, the direction of jet varies from 5° to 35°, as shown in FIGS. 10G-J. The simulation results clearly show these changes too. FIG. 10I shows the flow pattern and velocity distribution of the case the laser beam focuses slightly below a 20°-tilt-angle needle tip. In this case, the direction of jet is 5° to the horizontal direction. When laser beam focuses slightly above a 20°-tilt-angle needle tip, shown in FIGS. 10K and 10L, a jet with the direction of 35° can be generated. This also implies that tuning the focusing point on the needle tip will provide the same effect as tilting the needle direction and enables real-time remote control of the direction of the laser streaming. The disclosed technology enables laser streaming from the metal surface of the needle.

Referring to FIGS. A. 11A-I, an acoustic pressure field, an intensity contour, and a velocity distribution of laser streaming on the tip of the needle are shown. For a relatively large flat vibrating source, the acoustic pressure field near the source is similar to a plane wave, as shown in FIG. 11A. Interestingly, when the size of the vibrating source is reduced, the plane wave gradually turns to a spherical-like wave. FIGS. 11A-C show the changes in acoustic pressure field from 400 µm vibrating source down to 50 µm. A similar spherical-like acoustic pressure field is generated by the vibrating pressure distribution model of needle tip, shown in FIG. 11D. Thus, the needle tip can be considered as an extension of a classic model on a smaller scale. The intensity contour, in this case, is not concentric circles but rather a set of eccentric circles, as shown in FIG. 11E, and the gradient of the intensity follows a direction along the symmetry axis of the vibrating part. Since the direction of the acoustic force follows the gradient of the intensity, the jet will always follow the normal direction of the vibrating part on the needle tip, as shown in FIG. 11F. Similarly, when the vibrating part is slightly above the needle tip (shown in FIG. 11G), the direction of intensity gradient tilts up (shown in FIG. 11H), and the jet flows along the normal direction of the vibrating part as well (shown in FIG. 11I). Thus, the directional jet generated on the needle tip results from the small size of the vibrating source and the directional acoustic pressure field it generates, which is different from the acoustic streaming directly generated by sonotrode tips in a centimeter scale.

In aspects, the disclosed technology may be used for cleansing (e.g., microfluidic cleaning of an artery), drug delivery to an identified location, circulation, cutting membranes (e.g., cell membranes), and/or drilling membranes.

The aspects disclosed herein are examples of the disclosure and may be embodied in various forms. For instance, although certain aspects herein are described as separate aspects, each of the aspects herein may be combined with one or more of the other aspects herein. Specific structural and functional details disclosed herein are not to be interpreted as limiting, but as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present disclosure in virtually any appropriately detailed structure. Like reference numerals may refer to similar or identical elements throughout the description of the figures.

The phrases “in an aspect,” “in aspects,” “in various aspects,” “in some aspects,” or “in other aspects” may each refer to one or more of the same or different aspects in accordance with the present disclosure. A phrase in the form “A or B” means “(A), (B), or (A and B).” A phrase in the form “at least one of A, B, or C” means “(A); (B); (C); (A and B); (A and C); (B and C); or (A, B, and C).”

Any of the herein described methods, programs, algorithms, or codes may be converted to, or expressed in, a programming language or computer program. The terms “programming language” and “computer program,” as used herein, each include any language used to specify instructions to a computer, and include (but is not limited to) the following languages and their derivatives: Assembler, Basic, Batch files, BCPL, C, C+, C++, Delphi, Fortran, Java, JavaScript, machine code, operating system command languages, Pascal, Perl, PL1, scripting languages, Visual Basic, metalanguages which themselves specify programs, and all first, second, third, fourth, fifth, or further generation computer languages. Also included are database and other data schemas, and any other meta-languages. No distinction is made between languages which are interpreted, compiled, or use both compiled and interpreted approaches. No distinction is made between compiled and source versions of a program. Thus, reference to a program, where the programming language could exist in more than one state (such as source, compiled, object, or linked) is a reference to any and all such states. Reference to a program may encompass the actual instructions and/or the intent of those instructions.

It should be understood that the foregoing description is only illustrative of the present disclosure. Various alternatives and modifications can be devised by those skilled in the art without departing from the disclosure. Accordingly, the present disclosure is intended to embrace all such alternatives, modifications, and variances. The aspects described with reference to the attached figures are presented only to demonstrate certain examples of the disclosure. Other elements, steps, methods, and techniques that are insubstantially different from those described above and/or in the appended claims are also intended to be within the scope of the disclosure. 

What is claimed is:
 1. An apparatus for controlling a cylinder by a microfluidic stream, the apparatus including: a microtube including a fluid and a cylinder; a first laser-driven photoacoustic microfluid pump (LDMP); and a fiber optic element including a first end and a second end, the first end configured to be disposed on the first LDMP, and the second end configured to be disposed in a first end portion of the microtube, wherein the first LDMP is configured to generate a directional fluidic jet from the fluid and to push the cylinder in a first direction away from the second end of the fiber optic element.
 2. The apparatus of claim 1, wherein the first LDMP includes: a substrate having a first side and a second side; and a layer of photoacoustic material disposed on the first side of the substrate, the layer of photoacoustic material including nanoparticles and configured to generate a directional ultrasound wave in response to a laser beam impinging on the layer.
 3. The apparatus of claim 1, further comprising: a second LDMP; and a second fiber optic element including a first end and a second end, the first end disposed on the second LDMP, and the second end configured to be disposed in a second end portion of the microtube, wherein the second LDMP is configured to generate a directional fluidic jet from the fluid, and to push the cylinder in a second direction different than the first direction.
 4. The apparatus of claim 3, wherein the second end of the fiber optic element includes a surface implanted with metal.
 5. The apparatus of claim 4, wherein a first end of the second fiber optic element includes a surface implanted with metal.
 6. The apparatus of claim 1, wherein the cylinder includes a first end including a surface implanted with metal.
 7. The apparatus of claim 1, wherein the cylinder includes a second end that includes a surface implanted with metal.
 8. The apparatus of claim 1, wherein the fluid includes at least one of water, blood, plasma, or body fluid.
 9. The apparatus of claim 1, wherein the microtube is disposed on a microfluidic chip.
 10. A method for controlling a cylinder by microfluidic streaming, the method including: generating a directional ultrasound wave, in a microtube, based on directing a laser beam at a first laser-driven photoacoustic microfluid pump (LDMP), wherein the microtube includes a fluid and a cylinder; thermally expanding and contracting a photoacoustic layer implanted on an end portion of the cylinder in response to the laser beam striking the photoacoustic layer; and moving the cylinder in a direction away from the first LDMP based on the thermal expansion and contraction.
 11. The method of claim 10, further comprising: generating a second directional ultrasound wave, in the microtube, based on directing a second laser beam at a second laser-driven photoacoustic microfluid pump (LDMP); thermally expanding and contracting a second photoacoustic layer implanted on a second end portion of the cylinder, in response to the second laser beam striking the second photoacoustic layer; and moving the cylinder in a direction away from the second LDMP based on the thermal expansion and contraction.
 12. An apparatus for generating vortex in a microfluidic chip, the apparatus including: a laser-driven photoacoustic microfluid pump (LDMP) configured to generate a vortex; a transparent substrate; a fiber optic element including a first end and a second end, the first end disposed on the LDMP, and the second end configured to be disposed in a first surface of the substrate; and microchannels including a fluid.
 13. The apparatus of claim 12, wherein the transparent substrate includes an area implanted with metal.
 14. The apparatus of claim 12, wherein the second end of the fiber optic element includes a surface implanted with metal.
 15. The apparatus of claim 12, wherein the fluid includes at least one of water, blood, plasma, or body fluid.
 16. The apparatus of claim 12, further comprising: a second LDMP configured to generate a vortex; and a second fiber optic element including a first end and a second end, the first end disposed on a second LDMP, and the second end configured to be disposed in a first surface of the substrate.
 17. The apparatus of claim 16, wherein the first fiber optic element is inserted into the microfluidic chip at a first angle relative to a first surface of the microfluidic chip.
 18. The apparatus of claim 17, wherein the second fiber optic element is inserted into the microfluidic chip at a second angle relative to a first surface of the microfluidic chip, wherein the second angle is different than the first angle.
 19. The apparatus of claim 12, wherein the microfluidic chip is configured for microfluidic mixing of a sample with the fluid.
 20. The apparatus of claim 12, wherein the microfluidic chip is configured for at least one of microfluidic surgery or cleaning an artery. 